1. Field of the invention.
The present invention relates to ink jet printers, and, more particularly, to a method of printing using an ink jet printer.
2. Description of the related art.
Ink jet printers commonly include a printhead which is mounted on a carriage assembly. The carriage assembly is movable in a transverse direction, relative to an advance direction of a print medium such as paper. As the printhead is moved across the print medium during a particular pass of the carriage assembly, ink is selectively jetted from ink jetting orifices formed in the printhead and is deposited on the print medium at corresponding ink dot placement locations in the image area of the print medium. Since the printhead moves in a direction transverse-(e.g., perpendicular) to the advance direction of the print medium, each ink jetting orifice passes in a linear manner over the print medium. The line associated with each ink jetting orifice which overlies the print medium is commonly referred to as a raster or raster line. A plurality of rasters which extend across the image area of the print medium are disposed vertically adjacent to each other in the advance direction of the print medium.
Multi-color ink jet printers typically include a printhead having a plurality of ink jetting orifices therein. The ink jetting orifices are segregated into different arrays of ink jetting orifices, with each array corresponding to the different color inks which are to be jetted onto the print medium. With a known tri-color printhead, a first array of ink jetting orifices is used for jetting yellow ink onto the print medium, a second array of ink jetting orifices is used for jetting magenta ink onto the print medium, and a third array of ink jetting orifices is used for jetting cyan ink onto the print medium. The first, second and third arrays of ink jetting orifices are sequentially arranged relative to the advance direction of the print medium. Associated with each ink jetting orifice in the three arrays of ink jetting orifices is a corresponding ink jetting heater. Actuation of a particular ink jetting heater causes the formation of a bubble within the ink disposed adjacent thereto and expels the ink from the associated ink jetting orifice. A host computer connected with the printer transmits raster information to the printer for selective actuation of the ink jetting heaters.
To render a full color image, the tri-color printhead is passed across a print medium such as paper in a horizontal direction perpendicular to the vertical direction of alignment of the orifices in the printhead. Between passes of the printhead, the print medium is moved in the advance direction. For a raster, or row of printed dots, which contains at least one of each of cyan, magenta and yellow dots, the color printhead must be passed at least three times, once passing to deposit any cyan dots present in the given raster, once passing to deposit any magenta dots, and once passing to deposit any yellow dots. Of course, for any pass of the color head all 48 color orifices can be used, depositing the cyan, magenta, and yellow inks at different raster locations.
With known methods of printing with a tri-color printhead, a single carriage speed is selected prior to a print job and the carriage assembly is scanned during successive scans in opposite directions across the print medium at the same carriage speed. If a high quality print job is desired, the entire image is printed with a slower carriage speed. Conversely, if a draft or lower quality print job is acceptable, the entire image within the image area is printed at the faster carriage speed.
What is needed in the art is a method of printing with an ink jet printer which allows both print quality and printer performance to be optimized, where appropriate, while printing an image within an image area.